High pressure water tube boiler for locomotives



June 26, 1934.

H. NYFFENEGGER HIGH PRESSURE WATER TUBE BOILER FOR LOCOMOTIVES FiledJuly 2, 1931 00 ooooooooooo wmmaoowoooooooooo O I 0 0| 0 0 ANN N m ..OOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOO Ill.

O 0 w w 0 K O O O O0 0O 00 000000 MMQ Patented June 2%, 1934 UNITEDSTATES PATENT OFFICE HIGH PRESSURE WATER TUBE BOILER FOR LOCOMOTIVESAppiication July 2, 1931, Serial No. 548,422 In Germany November 3, 19305 Claims.

With high pressure water tube boilers, particularly for locomotives, thearrangement of the heating surfaces with a View to obtain a heatingeffect of the combustible gases as great as possible becomes a matter ofconsiderable difficulty. It is obvious with the process of evaporationthat in order to render the eliiciency of the boiler as great aspossible the heating surface in contact with the water is best separatedin two main parts. In a first part, i. e. in the flue gas heated icedwater preheater a proportion of heat as great as possible should betransmitted to the feed water which almost sufiices to heat the water upto the coiling point which corresponds to the pressure existing in theboiler and this is preferably efiected in a counter flow between thefeed water and the flue gases with the temperature of the lattergradually decreasing. In a second part it is essential that the heat tobe transmitted, corresponding to the evaporation taking place atsubstantially constant temperature, is emitted by the combustible gasesat a temperature as constant as possible i. e. the heat for evaporationis to be transmitted in the fire box heated by the flames set up on thegrate and the radiating gases. I have found by tests that the bestexploitation of the hue gases is reached when the relation of the sum ofthe heating surfaces of the fire box and the combustion chamber to thetotal heating surface in contact with th water of the boiler is about1:7.

In a third part of the heating surface, 1. e. the superheater, the wetsteam generated in the boiler is suitably transformed, by means offurther heat transmission into superheated steam. Thus, corresponding tothe high temperature for the superheated steam to be obtained thehighest in the whole process of evaporation, the superheater ought to bearranged in the highest region of the heating space. In respect of thelimited cooling effect of the superheated steam, however, and absence orany cooling eliect when the withdrawal of the steam is effected in aclosed chamber, it is impossible without the aid of special auxiliarymeans to arrange the superheater in this manner. But in order todistribute the means participating in the exchange of heat over thetemperature regions in the most suitable manner, the superheater ispreferably so inserted in the stream of the combustible gases that, atleast when the steam withdrawal is stopped, it is protected against theintensive heat radiation from the combustion chamber but heated by thehottest gases emanating from the fire box or the combustion chamberrespectively by surface contact.

The design of the steam generator is, however, not only dependent on theabove-mentioned requirements of the theory of firing and heattransmission, but also on the theory of circulation (water circulation),constructional reasons and requirements for cleaning purposes. Moreover,particularly with locomotives, the weight, space requirements and costof production play a decisive role.

The object of the present invention is to satisfy all theaboveunentioned requirements, by so designing the fire box as to permitthe transmission into the water of approximately that amount of heatnecessary for generating the total amount of steam in the boiler, at theboiling point of the water corresponding to the steam pressure. This isaccomplished by providing a relation between the total heating surfaceof the fire box covering sheet, inclusive of that of the combustionchamber and the total heating surface of the boiler in contact with thewater, which approximates the ratio 1:7.

With the proportions of these parts of the boiler according to theinvention approximating the said ratio the requirements for heatdistribution in the boiler as explained above are, as tests have shown,automatically met, the distribution of the heat admitted to the boilerwater depending for a certain constructional arrangement solely on theproportions of the respective parts.

The invention is schematically illustrated in the accompanying drawingin several constructional forms, by way of example only, in which:

Fig. l is a vertical longitudinal section of the boiler in assembly witha locomotive;

Fig. 2 is a section through the fire box on the line IIII in Fig. 1;

Fig. 3 is a section through the combustion chamber 0n the line IIIIII inFig. 1 ahead of the fire bridge;

Fig. 4 is a section on the line IVIV in Fig. 1 through the superheater;

Fig. 5 is a section on the line VV in Fig. 1 through the preheater;

Fig. 6 shows a top plan view of the preheater;

Figs. 7 to 9 show diagrams for difierent modifications of the preheater,and

Fig. 10 is a fragmentary vertical section similar to Fig. 1 showing amodified form of the boiler.

Referring to the drawing the general designations for all the figuresare 1 and 1 for the steam collecting drums (upper drums), 2 and 2' forthe lower or water drums, 3 are the inverted U-shaped tube elements ofthe fire box and 4 the pipe connections of these elements to the upperdrums. The U-shaped tube elements of the superheating chamber aredesignated by 5 and by 6 the rear end wall including the firing door '7and the protective lining 8. By 9 the forward end wall is designated and10 refers to the grate. 11 denotes the fire brick partition wallincluding the refractory arch 12. 13 are the water tubes of thecombustion chamber 18 which are connected by the tubes 14 to the stubdrum 15. The tubes 13 and 14 provide branch tubes between the upper andlower drums l, 1 and 2, 15, 2 respectively. 16 and 16' denote shortWater drums inserted in the forward end wall and connected by watercirculation tubes 17 to the drums l, 1, whilst the water circulationpipes 18 interconnect the drums, 1, 1' and 2, 2. 19 designates thesuperheater, 20 the chamber for disassembling purposes, 21 the feedwater preheater, and 22 exterior and 23 interior preheater tubes.

Fig. 1 shows a high pressure water tube boiler mounted in a locomotivewhich comprises the two large upper steam collecting drums l, 1 and thetwo lower or water drums 2, 2' which are disposed laterally of thegrate. The upper drums communicate with the lower drums by the rearwardwater circulation tubes 18. A great number of closely packed verticallyarranged U-shaped tubes 3, which are assembled in a known manner, form ashell for the fire box, the top sheet or ceiling of which protects theupper drums against being heated. The U-shaped tube elements areconnected to the lower drums 2, 2' by beads on their lower ends, andtheir tubular transverse members, forming the top sheet of the fire box4 communicate by means of the two short pipe connections 4 with the twoupper drums for discharging the steam generated in the tube elementsinto the two upper drums. The individual tube members of the U-shapedevaporating elements 3 can be mechanically cleaned through aperturesadapted to be closed by screw caps 3 in the corner connections. The rearend wall 6 of the fire box is formed in a manner known per se by a waterfilled double plate water header, which is rigidly connected to thedrums, and the plates of which are stiffened by staybolts or sleevesrespectively and which carries the firing door '7. As it is impossibleto clean the surfaces of the double plate walls which are in contactwith the water mechanically from depositing incrustations, these wallsare provided with a lining 8 on the furnace side for protecting the wallfrom being overheated, so that no particles that are apt to formincrustations are given an opportunity of binding on the metal. Theforward end wall 9 of the fire box or water header is constituted by adouble plate wall similar to the wall 6 and is formed with a largeapertureproviding sufiicient free passage for the gases toescape fromthe fire box. The forward double plate wall 9 is set back from theforward ends of the drums 1, 1 in substantial manner, i. e. for thedistance A which is at least the length of the superheater 19. Thedouble plate walls serve as supports for the two upper drums 1, 1 and toa certain extent also as water returns for facilitating the watercirculation, both plate walls communicating with the upper and lowerdrums 1, 1 and 2, 2 respectively, as shown at 25. The grate 10 in thefire box slants considerably forwardly so that its forward end extendsdown to the level of the lower drums 2, 2. The forward end of the grateadjoins the partition wall 11 of fire brick which serves at the sametime as a support for the re fractory arch 12. In the space between thissupporting wall for the refractory arch and the forward double platewall 9, i. e. the space which corresponds to the combustion chamber ofgreat low pressure locomotive boilers and which for high pressureboilers forms an annex to the fire box, three additional longitudinalrows of steeply ascending water tubes are arranged, the two outer rows13 of which are fed from the lower drums, their upper ends communicatingwith the top tube elements of the fire box or the connecting pipesbetween these elements and the upper drums respectively. The middle row14 of water tubes is fed from a small stub drum 15, the forward end ofwhich is jointed with the forward double plate wall, and the steamgenerated in said row of tubes is delivered to the tube element formingthe top sheet of the fire box at the mid point of these elements. As inthe combustion chamber 18 the heat radiation is considerably diminishedthe generated steam has sufficient free passage for flowing to the upperdrums. The additional water tubes in the combustion chamber tend todiminish the heat radiation between the fire box and the superheater andare adapted to be mechanically cleaned partly from the upper drums andpartly through apertures provided in the tube elements of the top sheetof the fire box adapted to be closed by threaded caps 13', 14.

The heating surface of the fire box inclusive of the combustion chamberis so designed as to permit the transmission into the water ofapproximately that amount of heat necessary for generating the totalamount of steam of the boiler at the boiling point of the watercorresponding to the steam pressure. The fire box designed from thispoint of view produces due to its size relatively lower temperatures,which with a view to safeguarding the heating surfaces as much aspossible is very desirable. The relatively large combustion chamber 18which produces a relatively low speed of the combustion gases promotesthe combustion of fine coal ;5-

particles which may have been carried off. After leaving the fire box 4'and the combustion chamber 18' the heating gases enter the superheatingchamber 24. The latter is formed in similar manner as the covering sheetof the fire box by U-shaped tube elements 5. These tube elements join atthe bottom with the two short drums 16, 16 which are connected to theforward plate wall 9 and which are disposed on a somewhat higher leveland eventually further away from the middle than the lower water drums2, 2' of the fire box 4. The U-shaped tube elements of the superheatingchamber 24 are connected in similar manner as the tube elements of thefire box 4 with the large upper chamber 24 may be protected by a heatinsulating lagging against heating.

Unless otherwise required by constructional reasons the circulationtubes are vertically arranged, i. e. so as to provide the shortestbridge between the drums. The drums are apertured at the places wherethey pass through the water space of the double plate walls as at 25 soas to increase the section of free passage for the water circulation asmuch as possible.

The superheater 19 is aranged in the abovedescribed superheater chamber24 and constructed as a cross-stream heat exchange device includingvertical tubes. At top it is removably connected at 38 on the one handto a steam collecting piping 3? for conducting the steam from the upperdrun s 1, l to the superheater and including a control valve 37 and onthe other hand to a pipe 38 leading to the throttle valve 38. It restson a longitudinal slide or track or as shown on a roller grate 26connected to the bottom 27 of this chamber which in turn is suspendedfrom the short drums 1 15' by means or a carrier 28. The weight of thesuperheater transmitted to the short drums 16, 16 is transferred to thesteam collecting drums 1. 1 by the shell of the boiler. The superheaterwhich is detachably arranged adapted to be shifted as whole towards thefront into the chamber 2'0 for disasseml ing p'u poses and after removalof the cover 29 read of the steam collecting drums l, the superl'ieater19 may be taken out of the boiler if desired. In this manner large areasof free passage are provided to give convenient access to the uperheatercharnber 24, combustion chamber 18, fire box 4. and the forwardlydisposed flue gas feed water preheater 21. The superheater 19 may beplaced further forwardly in the superheater chamber (see Fig. 10) andthe space thus made available in the superheater chamber equipped withwater tubes similar to those in the combustion chain her. With thisarrangement the carrier 28 is directly connected to the frame of thelccomo tive.

The line gas feed water preheater 21 is subdivided into a number ofregions consecutively connected with each other for conducting the fluegases in longitud nal planes in a counter flow to the feed water. Thehottest region I of the preheater (see Fig. l) is disposed with itsupper edge substantially at the same level as the upper edge of thesuperheater chamber 24. The second or middle region II of the preheateris positioned beneath the first region and is passed by the flue in theopposite direction as the region I. The third or coolest region isplaced below the second region and is passed by the gases in the samedirection as the first region. The tubes 22 extericrly disposed at thesides of the first and the second region respectively are prolongedrearwardiy as at 30 to extend adjacent to the circulation tubes 5, ofthe superheater chamber thus forming cooled side walls for the chamber20 for disassembling purposes. Corresponding to the amount of coolingand the decrease in the volume of the flue gases the cross sections orfree passage for the gases are reduced from region to region with a viewto keep the speed of the gases constant. Contructional reasonsoccasioned by the requisite distribution of weight may necessitate theomission of the tube elements in one of the regions so that therespective region will then serve as a conduit for the gases only. Theregions are separated by horizontal separating slabs 30 overlying thelongitudinal preheater tubes. The ends of the regions are interconnectedby easily detachable connector plates 31, 31. The exterior preheatertubes 22 adjacent the shell of the boiler are of larger diameter thanthe interior tubes 23 of bundles of tubes, so that the tubes 22 contacteach other longitudinally, thus preventing the hot gases from sweepingthe shell of the preh ater. The bundles of water tubes of the individualregions are interconnected by detachable bend connectors 32 so as toprovide a continuous conduit for the ice water to pass through incounter flow to the flue gases. Alternatively, the regions of thepreheater may be so arranged that the hottest region is situated at thebottom and the coolest region at the top as schematically represented inFig. '7, or the second and third regions may each be divided in twoducts connected in parallel and disposed in symmetrical dispositionabove and below the first and hottest region I respectively (Fig. 8),the said parallel connected ducts being passed by the fine goes in thesame direction. In Fig. 9 a modification of 8 is shown which is obtainedby turning the arrangement shown in Fig. 8 through an angle of 953, sothat the separating slabs for the regions lie in vertical longitudinalplanes of the locomotive. The cinders accumulating in the combustionchamber and the chamber for disassembling the superheater may be eductedthrough special funnels lined with masonry.

The part of the boiler constituted by the various drums i. e. the partwhich serves for evaporating inclusive of the superheater and the fluegas heated feed rater preheater are separately mounted on thelongitudinal frame of the locomotive. The forward end portion of theboiler is formed in usual manner by a smoke box from which the fluegases are discharged into the open by means of a blast nozzle applianceas or a ventilator respectively. At 35 an exhaust steam feed waterheater is shown from which the water passes preheated to a temperatureof from to 100 C. to the region III of the flue gas heated feed waterpreheater, through a connecting pipe 39. The other end of the preheater21 communicates with the drums l, l by way of the pipe 40.

The water is admitted to the exhaust steam feed water heater 35 by meansof a pipe 41 and an injector 41 which draws it from the tender notshown) in a known manner.

I claim:

1. In a high pressure boiler for locomotives, in combination, a fire boxhaving a fire bridge, the rear portion of said fire box behind said firebridge constituting a combustion chamber, water tubes forming the sidewalls and ceiling of said lire box, at least one upper steam collectingdrum con municating with said water tubes and protected by the same frombeing heated said fire box, a superheater for the steam accumulated insaid upper drum communicating with the latter, lower water drumscommunicating with said water tubes, forward and rearward headerscommunicating with said upper and lower drums for providing circulationof the water, branch tube elements arranged between said upper and lowerdrums, water circulation tubes communicating with said upper and saidlower drums, and a line gas heated feed Water preheater being subdividedinto a number of sections arranged to heat the feed water in a counterflow to the flue gases connected with said upper drum, the wholearrangement being such that the total heating surface of said fire boxinclusive of that of said combustion chamber in relation to the totalheating surface in contact with the water of the boil er is about 1:7.

2. In a high pressure boiler for locomotives in combination, a fire boxhaving a fire bridge, the rear portion of said fire box behind said firebridge constituting a combustion chamber, water tubes forming the sidewalls and ceiling of said fire box, at least one upper steam collectingdrum communicating with said water tubes and protected by the same frombeing heated by said fire box, a superheater for the steam accumulatedin said upper drum communicating with the latter, a forward extension onsaid upper steam collecting drum projecting at least to the front end ofsaid superheater, a superheating chamber for accommodating saidsuperheater and positioned underneath said forward extension of saidupper steam collecting drum, lower water drums communicating with saidwater tubes, forward and rearward water headers communicating with saidupper and lower drums, for providing circulation of the water, branchube elements arranged between said upper and lower drums, and a fiue gasheated feed water preheater being subdivided into a number of sectionsarranged to heat the feed water in a counter flow of the flue gasesconnected with said upper drum, the whole arrangement being such thatthe sum of the heating surface of said fire box inclusive of that ofsaid combustion chamber in relation to the total heating surface incontact with the water of the boiler is about 1:7.

3. In a high pressure boiler for locomotives, in combination, a fire boxhaving a fire bridge, the rear portion of said fire box behind said firebridge constituting a combustion chamber, water tubes forming the sidewalls and ceiling of said fire box, at least one upper steam collectingdrum communicating with said water tubes and protected by the same frombeing heated by said fire box, a superheater for the steam accumulatedin said upper drum communicating with the latter, a disassemblingchamber situated forwardly of said superheater and adapted to receivesaid superheater temporarily, lower water drums communicating with saidwater tubes, forward and rearward water headers communicating with saidupper and lower drums for providing circulation of the water, branchtube elements arranged between said upper and lower drums, watercirculation tubes communicating with said upper and lower drums, a fiuegas heated feed water preheater connected with said upper drum,longitudinal exterior and interior water tubes in said preheater, theexterior tubes having a larger diameter than the interior tubes andcontacting each other longitudinally, rearward. extensions of saidlongitudinal water tubes of said preheater providing side walls for saiddisassembling chamber, separating bafiles arranged between said watertubes inside said preheater, and succeeding horizontal heating sectionsprovided by said separating baffies and having a cross-section adaptedto conduct the escaping gases in a counter flow to the feed water atsubstantially uniform speed, the whole arrangement being such that thetotal heating surface of said fire box inclusive of that of saidcombustion chamber in relation to the total heating surface in contactwith the water of the boiler is about 1:7.

4. In a high pressure boiler for locomotives, in combination, a fire boxhaving a fire bridge, the rear portion of said fire box behind said firebridge constituting a combustion chamber, water tubes forming the sidewalls and ceiling of said fire box, at least one upper steam collectingdrum communicating with said water tubes and protected by the same frombeing heated by said fire box, lower water drums communicating with saidwater tubes, forward and rearward water headers communicating with saidupper and lower drums for providing circulation of the water, branchtube elements arranged between said upper and lower drums, a superheaterfor the steam accumulated in said upper drum communicating with thelatter and disposed forwardly of said branch tube elements to beprotected by the same, and a fine gas heated feed water preheaterarranged forwardly on the locomotive and connected with said upper drum,the whole arrangement being such that the total heating surface of saidfire box inclusive of that of said combustion chamber in relation to thetotal heating surface in contact with the water of the boiler is about1:7.

5. In a high pressure boiler for locomotives, in combination, a fire boxhaving a fire bridge, the rear portion of said fire box behind said firebridge constitutin a combustion chamber, water tubes forming the sidewalls and ceiling of said fire box, at least one upper steam collectingdrum communicating with said water tubes and protected by the same frombeing heated by said fire box, lower water drums communicating with saidwater tubes, forward and rearward water headers communicating with saidupper and lower drums for providing circulation of the water, branchtube elements arranged between said upper and lower drums, a superheaterfor the steam accumulated in said upper drum communicating with thelatter and disposed forwardly of said branch tube elements to beprotected by the same, a disassembling chamber situated forwardly ofsaid superheater and opening to said superheater to receive the sametemporarily while being taken out of position of use, and a flue gasheated feed water preheater being subdivided into a number of sectionsarranged to heat the feed water in a counter flow to the flue gasesconnected with said upper drum, the whole arrangement being such thatthe total heating surface of said fire box inclusive of that of saidcombustion chamber in relation to the total heating surface in contactwith the water of the boiler is about 1 7.

HANS NYFFENEGGER.

